This application is related to a commonly assigned co-pending application filed simultaneously herewith entitled xe2x80x9cVIDEO DISPLAY SYSTEM WITH TWO CONTROLLERS EACH ABLE TO SCALE AND BLEND RGB AND YUV SURFACESxe2x80x9d, the specification of which is hereby incorporated by reference.
The present invention relates to a single controller system for multiple display output including motion video output.
Video display controllers are known which are able to work with both RGB pixel format and YUV pixel format to combine two display surfaces from graphics memory to provide an overlay output. This is useful, for example, in the situation that a movie source in YUV format is obtained by decoding a video file from say a CD-ROM or DVD device, and written to a video surface in graphics memory. At the same time a computer environment desktop is stored in RGB format in another surface within graphics memory. These two surfaces can be combined to provide the YUV source within a window on the desktop. Because the video display controller handles the conversion, scaling and mixing of the two sources, the computer operating system or application program does not directly create the desired display, but rather instructs the display controller system to scale and combine the two sources as desired. The quality of display and efficiency of the computer system is thereby greatly enhanced.
In such display controller systems capable of supporting dual display output, when YUV pixel format video is overlaid or blended with a graphics or RGB surface, both displays operate in a simultaneous mode in which the same output is shown on both displays. Therefore only one combined output of mixed format video is possible in which case the second output can only mirror what is being displayed by the first output.
It has been found that it would be desirable to provide full screen motion video output on a display device such as for example a TV while at the same time providing a computer desktop display in which the motion video is displayed overlaid within a window on the desktop surface. The state of the art display controller systems are not able to provide such operation within one graphic controller system having a single memory subsystem While possible to make use of two display controller systems which both must be controlled to share the computer""s resources to provide the desired dual display output, this is not known in the art, because of various limiting factors, including cost, strain on the computer""s resources and the need to control and synchronize the two display controller systems at the driver level and possibly also at the application or operating system level.
It is a general object of the present invention to provide a display controller apparatus for multiple display devices, the apparatus being able to output motion video on one display at the same time as a computer desktop is output on another display, in which drawbacks of the prior art are overcome. Firstly, it is an object to provide a display device controller apparatus able to provide motion video overlay on a first desktop display, while at the same time provide full screen the motion video on a second display. Secondly, it is an object to provide a display device controller apparatus able to provide an automatic control for outputting full screen the motion video on a second display when a request is made to provide an overlay. Thirdly, it is an object to provide a display device controller apparatus able to automatically determine whether scaling is required to provide full screen motion video output, and if scaling functionality is available then invoking scaling, and otherwise padding or cropping the motion video before outputting to the second display. Fourthly, it is an object to provide a display device controller apparatus having sufficient 2D or 3D drawing engine capability that scaling, overlaying and/or blending of motion video can be done in video memory without having to rely on dedicated scalers, multiplexers or blending units in each display controller path to provide those image processing functions. The invention provides both a display controller apparatus as well as a method for providing a multiple display device output and a method for controlling a display controller apparatus.
According to the invention, there is provided a multiple display device display controller apparatus comprising a video memory containing a main display surface and a YUV format video surface, a first display controller accessing the main display surface and the YUV format video surface and outputting a display signal, the first display controller including a scaler unit and an overlaying unit for overlaying the YUV format video surface on the main display surface, and a second display controller accessing the YUV format video surface from the video memory and outputting a display signal to provide full screen output. Advantageously, the apparatus also preferably detects an overlay request from the application decoding the video, or an equivalent indication from the computer that a user has requested the display of motion video in a window of the desktop. In response to the detection of the overlay request, the apparatus overlays the YUV format video surface with the at least one other surface, and the second display controller is caused to automatically access the YUV format video surface and output full screen video from the YUV format video surface.
According to the invention, there is also provided a method of controlling a display controller apparatus connected to a computer and having at least two display device outputs. The method comprises the steps of:
detecting an overlay request generated in the computer, the overlay request indicating that a YUV format video surface is to be overlaid over a main display surface;
responsive to the detecting of the overlay request, causing the apparatus to access the YUV format video surface and to provide full screen output of the YUV format video surface on one of the at least two device outputs; and
causing the main display surface to be output on another of the at least two device outputs with a window portion of the main display surface intended to contain the YUV format video being one of minimized and blanked.
According to the invention, there is further provided a method of controlling a display controller apparatus connected to a computer and having at least two display device outputs. The method comprises the steps of:
storing in a video memory of said apparatus a main display surface and a YUV format video surface;
causing a first display controller of said apparatus to access said main display surface and said YUV format video surface and to output a display signal to a first display, the first display controller including a scaler unit and an overlaying unit;
causing said first display controller to overlay said YUV format video surface on said main display surface; and causing a second display controller to access said YUV format video surface from said video memory and to output a display signal providing full screen output to a second display.
Preferably, the method according to the invention further comprises detecting a resolution of the YUV format video surface and determining whether the YUV format video surface requires scaling. In one embodiment, when scaling is required, the YUV format video surface is caused to be scaled. However, in another embodiment, when scaling is required, the full screen output of the YUV format video surface is not implemented. In this case, when the controller apparatus does not have scaling capacity and the YUV video is not in a same resolution as the display device connected to the one of the device outputs, automatic full screen video output is not performed. In a further embodiment, when scaling is required, the YUV format video surface is caused to be padded or cropped, as needed. In this embodiment, the controller apparatus does not have scaling capacity and the YUV video is not in a same resolution as the display device connected to the one of the device outputs, full screen video output is performed with padding or cropping.
It is also preferable that the second display controller be caused to stop displaying a surface other than the YUV format video surface and to begin displaying the YUV format video surface when the overlay request is detected. The full screen display is preferably a TV, and the YUV format video surface may be obtained from a full resolution DVD (MPEG-2) source. In this way, the YUV format video surface does not typically require scaling and the full screen output on the TV is performed.
It is also preferable that either controller have blending capabilities so that motion video over graphics overlay and graphics over motion video blending can be performed.